Task: Write Alphabet Forward-Backward Feature function: delta_pause_ratio

[kimit0310]

Description

New functions are needed to compute forward-backward comparison metrics for the alphabet task. The delta_pause_ratio function will calculate the difference in pause ratio between the forward (A→Z) and backward (Z→A) conditions.

Tasks

• Ensure both DataFrames contain the seconds column needed for pause detection
• Reuse the pause ratio helper to derive per-condition pause ratios (default threshold 0.1s)
• Compute delta_pause_ratio = forward_pause_ratio - backward_pause_ratio
• Return the result as a float

Freeform Notes

If the pause helper is not yet extracted, create a shared utility so both single-condition and delta metrics use identical logic.